Method of producing aromatic hydrocarbons

ABSTRACT

METHOD OF PRODUCING AROMATIC HYDROCARBONS WHICH COMPRISES HYDROFORMING A HYDROCARON AT A TEMPERATURE FROM 300*C. TO 650*C. OVER A CATALYST COMPRISING PLATINUM AND LEAD PREPARED BY AN IMPREGNATION PROCEDURE.

Ag- 5, 1974 NAoYA KoMlNAMl Erm. 3,827,972

METHOD 0F PRODUCING ROMATIC HYDROCRBONS Filed Nov. 18, 1971 m t E Tl. PB b A P B P o/h A 6 W u 5 A 5 O. m y mn 4 /x -3 X l 2 .H v LE Pm 5m ,lO( llulcqul." l u l u 1 v n u .A O O O O O 5 4 3 2 l Olm; mgomq UnitedStates Patent O Mice U.S. Cl. 208-139 8 Claims ABSTRACT OF THEDISCLOSURE Method of producing aromatic hydrocarbons which compriseshydroforming a hydrocarbon at a temperature from 300 C. to 650 C. over acatalyst comprising platinum and lead prepared by an impregnationprocedure.

RELATED APPLICATIONS This application is a continuation-in-part of ourapplication Ser. No. 6,948, iiled Ian. 29, 1970. It is related toapplications: Ser. No. 200,065, which is directed to the catalystsdescribed in this application; Ser. No. 200,023 which describeshydroforming of a hydrocarbon charge with a Pt-Pb catalyst prepared by asequential impregnation method wherein Pt is first supported on acarrier prior to supporting Pb on the carrier; and Ser. No. 200,- 071which describes hydroforming of a hydrocarbon charge with a Pt-Pbcatalyst prepared by coprecipitation; all tiled concurrently herewith.

BACKGROUND OF THE INVENTION Field of the Invention This inventionrelates to a method of producing aromatic hydrocarbons from petroleumsources at high yields. More particularly, it is concerned with a methodof producing a distillate of high aromatic concentration in high yieldby highly selectively subjecting naphthenic hydrocarbons todehydrogenation and paraftinic hydrocarbons to dehydrocyclization.

Description of the Prior Art A number of investigations have been madeheretofore on methods for producing aromatic hydrocarbons from petroleumsources to establish several industrial processes employing catalystscomprising platinum, chromina, molybdena and the like. In theseprocesses, naphtha is used as the starting material, which is subjectedto catalytic reaction in gas phase at a high temperature. The liquidproduct thus produced contains isomers of parainic hydrocarbons at ahigh concentration and is often used as gasoline for motor cars, etc.because of its high octane number. However, its content of aromatichydrocarbons is so low that an additional extraction or dealkylationstep is needed in order to obtain benzene, toluene, xylene and the like.In addition, the yield of aromatic hydrocarbons based on the startingmaterial employed is so low that the operation of these steps is costly.

On the other hand, demand for aromatic hydrocarbons is being increasedrapidly due to rapid growth of industries related to aromatics such asplastic and synthetic ber industries. In this respect, it has becomenecessary to develop a process for producing aromatics in a higheryield. Moreover, the gasoline industry needs higher and higher octanenumbers.

3,827,972 Patented Aug. 6, 1974 of production because it depends uponthe production of ethylene.

SUMMARY OF THE INVENTION As a result of extensive investigations on theprocess commercially advantageous in consideration of the source anddemand of aromatics as well as the process economy as mentioned above,we have discovered a process with many advantages including the improvedyield of aromatics. The present invention, derived from the discovery,is concerned with a method of producing aromatic hydrocarbons whichcomprises treating a hydrocarbon or a hydrocarbon mixture at atemperature from 300 C. to 650 C. over a catalyst comprising platinumand lead or a catalyst comprising platinum, lead and at least a memberselected from lithium, sodium, potassium, rubidium, cesium, beryllium,magnesium, calcium, strontium, barium, zinc, cadmium, mercury,germanium, bismuth, chromium, molybdenum, tungsten, uranium, rhenium,ruthenium, rhodium, palladium, osmium and iridium. The catalyst isprepared by an impregnation procedure.

According to this invention, a variety of advantages may be enjoyed ascompared with prior methods as set forth below.

First, benzene, toluene, Xylenes and polymethylbenzenes are produced byquite simple procedures at low cost because of high concentration andyield of aromatics in the reformate produced according to thisinvention. vFor example, a distillate of higher boiling point thantoluene or xylene in the reaction product contains neither paraffin nornaphthene and then separation can be effected by distillation only,without application of solvent extraction. Such a distinction from theprior processes is ascribed to high activity and selectivity of thecatalyst of this invention in terms of aromatic formation, namelydehydrogenation or dehydrocyclization reactions.

In other words, in the conventional reforming processes knownheretofore, since hydrocracking, isomerization, dehydrogenation ordehydrocyclization are the main reactions involved, an attempt to obtaina liquid fraction having a high aromatic concentration leads to anincrease in hydrocracking with attendant results in low liquid yield anddegraded economy. If on the other hand, the liquid yield is made higher,then the paraffin concentration in the resulting liquid becomes higher.

However, when the catalyst of the present invention is employed, quiteunexpectedly, hydrocracking and isomerization are suppressed remarkablywhile dehydrogenation of naphthene or dehydrocyclization of paratiinoccurs preferentially, and, in addition, the catalyst activity is quitehigh.

While lead has been shown to be a poison for a platinum catalyst inhydroforming catalyst (U.S. Pat. No. 3,001,811 of Murray et al.), it hasbeen found that particular Pt-Pb combinations containing specified Pbcontents in specied P'b/ Pt ratios are excellent hydroforming catalysts.If the amount of Pb supported on a carrier with Pt is excessive, Pbexhibits a poisoning effect. Also, if the ratio of Pb to Pt on a carrierexceeds a specified value, then the Pb catalyst is poisoned. Influencingthe effectiveness of the catalysts also is the method by which they areprepared. Surprisingly, then, when the amount o of Pb is controlledWithin prescribed limits, the Pb/Pt ratio is also so controlled, and aparticular method of aszrpra preparation is selected, hydroformingcatalysts of high activity and high selectivity can be obtained.

Thus, utilization of features of the present invention as describedabove serves to produce aromatics having high carbon numbers from highboiling fractions having high carbon numbers such as, for example,kerosene and gas oil, in high yields. The same thing applies to naphthaand the process of the present invention affords far higher yields inthe production of trimethylbenzene, durene and the like than knownprocesses.

Secondly, purity and yield of the hydrogen are so high that hydrogen canbe supplied at a low cost.

Thirdly, life of the catalyst of this invention is so long thatfrequency in regeneration of the catalyst is reduced under normalreaction conditions in industrial operation.

Fourthly, the catalyst of this invention is operative at lower pressuresthan in prior processes. As the rate of degradation in activity in theprior catalysts is much more drastic and they become inoperative duringlong operation, and, therefore, the process on an industrial scale d hasto be carried out under high pressures. On the contrary, the catalyst ofthis invention is stable in the course of a long operation to give ahigh yield of aromaties.

As the platinum component of the catalyst, there may be used, forexample, the hydroxide, platinum halides, chloroplatinic acid or hydrateor ammonium salt thereof. Especially preferred are substances containinga halogen. This is due to the fact that in a compound containingplatinum and halogen, the halogen and especially chlorine present in thecompound advantageously contribute to the catalytic activity li-ke inother platinum reforming catalysts. The preferable amount of chlorinecontained in the catalyst of the present invention is in the range of l0.1-2.0% by Weight and particularly in the range of 0.5-

1.5% by weight based on the total weight of catalyst components. As thelead component, there may be employed halogenides, inorganic and organicsalts, hydroxide, oxide and the like. The element used as the thirdcomponent may be in the form of its oxide, hydroxide, halide or otherinorganic and organic salt or complex. The platinum, lead and the thirdcomponents may be in the form of a salt containing each of them.

Contents of the platinum, lead and the third components are 0.\l5% byweight, Q01-5% by weight and 0-3% by weight, respectively, andpreferably 0.05-l% by weight, Q01-3% by weight and 0-1% by weight,respectively based on the total weight of catalyst components, with theratio of lead to platinum ranging from 0.1 to 3.

The catalyst is prepared by simultaneously supporting platinum and leadon a carrier by conventional impregnation methods; or by supporting leadon a carrier and thereafter supporting platinum on the carrier, againusing conventional impregnation methods. Preferred Pb/Pt ratios, leadand platinum contents, and third component content with the twoimpregnation methods are as follows:

Simultaneous Pb, th en Pt impregnation impregnation Pb, percent wt; 0.l.2 0. 1-2. 5 0. 1- l 0. 1-1 0. 8-2 0. 3-2. 5 3rd component, percent Wt-0-1 0-1 4 calcined at a temperature from 400 C. to 700 C., preferably450 C. to 600 C.

In the sequential impregnation method, the catalyst is prepared byimmersing a carrier in an aqueous solution containing a lead compoundsuch as, eg., lead nitrate and lead chloride, to support the leadcomponent on the carrier, drying the resulting material and thencalcining the dried product at a temperature ranging from 300 C. to 800C. The calcined product is then immersed in an aqueous solutioncontaining a platinum compound such as, eg., chloroplatinic acid, tosupport the platinum component thereon, drying the resulting assemblyand then calcining the dried product at a temperature ranging from 400C. to 700 C., preferably from 450 C. to 600 C.

In the simultaneous impregnation method and in the sequentialimpregnation method mentioned above, amounts of platinum, lead and athird component contained in the solution of platinum compound, leadcompound and third component are, in general, 0.01-5 wt. percentplatinum; 0.01-5 wt. percent lead and 0-3 wt. percent third component.However, in the simultaneous impregnation method, the ranges preferablyare 0.1-l wt. percent platinum; 0.1-2 wt. percent lead and 0-1 wt.percent third component. On the other hand, in the sequentialimpregnation method, the ranges preferably are 0.1-1 Wt. percentplatinum; 0.1-2.5 wt. percent lead and 0-1 Wt. percent third component.

Lead to platinum weight ratio in the solution generally ranges from 0.1to 3.0, and preferably, in the simultaneous impregnation method, itranges from 0.3 to 2.0, and in the sequential impregnation method, itranges from 0.3 to 2.5.

The effective Pb/Pt ratio varies depending upon the process for thepreparation of catalyst and upon the reaction pressure. In case of usingthe catalyst prepared by the process of the present invention underatmospheric pressure and reaction pressures of 5 kg./cm.2, 10 kg./cm.2and not less than 20 kg./cm.2, the maximum effective Pb/ Pt ratios are3.8, 3.5, 3.2 and 3.0, respectively. This will be illustrated by theexamples as set forth hereinafter.

As with the conventional catalysts, the proportion of contents of thecomponents depends, for example, upon the type of carrier, surface area,order of the addition, method of the calcination and the like.

In order to increase the activity of the catalyst, the use of a carriersuch as silica alumina, alumina, alumina hydrate, silica, zeolite,kaolin, acid clay or bentonite is effective and preferable carriers arealumina, silica alumina, zeolite and the like.

The hydrocarbons which may be used in the present invention as thestarting material include those mainly comprising paraffins, olelins andnaphthenes having a boiling point Within the range of from 40 to 350 C.,which may be used alone or in admixture of two or more kinds. Preferablehydrocarbons are those having from 6 to l2 carbon atoms.

Most advantageous materials from the industrial standpoint are naphthashaving a boiling range of 40-190" C., kerosene having a boiling range of-260 C., and gas oil having a boiling range of 220-350 C.

Feeding ratio of hydrogen to hydrocarbon in gas volume is from 0.5 to l5and preferably from 2 to l0. Prior to the reaction, the catalyst may bepretreated with hydrogen at or near the reaction temperature to activateit.

Feeding rate of the hydrocarbon in terms of LHSV, which stands forliquid hourly space velocity (the feeding amount of hydrocarbon per unittime, per unit volume of catalyst, in ml.) is from 0.2 to l0 hr.1 andpreferably from 0.5 to 5 hrl.

Temperatures from 300 C. to 650 C., preferably from 430 C. to 580 C.,are employed for the reaction.

The reaction pressure is dependent upon the desired quality of productand economy and may be optionally chosen within the range of from 1 to50 kg./cm.2 and preferably from 5 to 20 kg./cm.2. In order to. improvethe space time yield in the commercial productlon, the reaction ispreferably carried out under an elevated pressure.

DESCRl'PTION OF PREFERRED EMBODIMENTS In order to illustrate theinvention examples are given below.

Example 1 In an aqueous solution of a mixture of chloroplatinic acid andlead chloride was immersed fy-alumina. After being dried, the resultingmass was calcined at 550 C. for 2 hours to prepare a catalyst with acomposition: 0.5% Pt-0.25% Pb-Al2O3. Percent is by weight herein unlessotherwise noted.

Through a catalyst layer containing 20 ml. of the catalyst, which washeated in advance in the presence of hydrogen at 500 C. for 2 hours, waspassed a gaseous mixture of hydrogen and n-heptane at a molar ratio of 3:1 at an LHSV of 0.5 hr.-1 under atmospheric pressure, while maintainingthe layer at a temperature of 490 C. The average molar yields of theproducts in hours were: Benzene 2.2% toluene 63.5% and xylenes includingethylbenzene 2.1% and the total aromatics 67.8%.

Example 2 A hundred milliliters of a catalyst prepared by the samemethod as in Example 1, the composition being 0.5% Pt-0.5% Pb-A12O3, washeated under hydrogen at 500 C. for 2 hours. Through the catalyst layer-was passed a gaseous mixture of hydrogen and naphtha with thecomposition given below at a feeding ratio of 3:1 (by gas volume) at anLHSV of 2.0 hr.1 under a total reaction pressure of 10 kg./cm.2 (gauge)continuously for 48' hours, 'while maintaining the layer at atemperature of 500 C. Yields by weight of the products were: Hydrogen4.5%, benzene 5.4%, toluene 15.3%, xylenes 30.6% and the total aromatics76.7%.

Component of the naphtha source (percent by volume) Parains 65.7 Olens 0Naphthenes 22.8 Aromatics 11.5

Example 3 Composition of the starting material (percent by volume):

Parains 65.5 Olens 0.2 Naphthenes 23.7 Aromatics 10.6

Example 4 With 100 cc. of a catalyst composition comprising 0.5%platinum, 0.5% lead and 'y-alumina was supported 0.3% potassiumcarbonate by impregnation and after the catalyst was reduced by hydrogenfor an hour at 530 C., a gaseous mixture of hydrogen and naphtha havinga composition shown below in a volume ratio of 10:1 was passedtherethrough at an LHSV of 1.0 hr.-1 at a reaction temperature of 480 C.under a reaction pressure of 4 kg./ cm.2 (gauge).

Composition of the starting naphtha:

Ingredient: Vol. percent Paratins 65.5 Oleins 0.2 Naphthenes 23.7Aromatics 10.6

As a result, the yields of the reaction products based on the startingnaphtha were as follows:

Catalyst composition: Pt-Pb-KzCOs Example 5 'y-Alumina granulated in aball of a diameter of 2 mm. was immersed in an aqueous solution ofrubidium hydroxide, followed by drying and calcination at 570 C. to givea carrier of the composition 0.21% rubidium- 99.79% A1203. The carrierwas then immersed in an aqueous solution of a mixture of chloroplatinicacid and lead chloride. After being dried in 2 hours and calcined at 550C. for 2 hours, there was prepared a catalyst of the composition:0.5%Pt0.5%Pb-0.2%Rb-Al203. A reactor 1.25 inches in diameter was filledwith the catalyst and treated under hydrogen for 45 minutes during whichperiod the temperature was raised from 410 C. to 530 C. A gaseousmixture of hydrogen and naphtha with the composition given below in aratio of 7.5 :1 was passed through the reaction tube at an LHSV of 2.0hr.-1 and a temperature of 510 C. under a pressure of 10 kg./ cm?.Yields by weight on average of the products after 25 hrs., on thenaphtha basis, were: Benzene 4.4%, toluene 14.9%, xylenes 33.6% and thetotal aromatics 77.9%.

Composition of the naphtha source (percent by volume):

Parains 55.2

lOlefins 0.1

Naphthenes 31.3

Aromatics 13.4

Example 6 Benzene 2.9%, toluene 13.3%, xylenes 29.3% and the totalaromatics 71.5%.

Examples 7-27 Twenty milliliters of a catalyst comprising 0.5% platinum,0.2% lead and a third component were heated at 500 C. for 2 hours in thepresence of hydrogen. Through the catalyst layer was passed a gaseousmixture of hydrogen and n-heptane in a molar ratio of 5:1 at an LHSV of0.5 hr.-1 under atmospheric pressure, while maintain- I ing the layer at510 C. Molar yields of aromatcs were as follows:

8 a carrier, then, after vaporized to dryness, calcined at 550 C. for 3hours, and, subsequently, immersed in 200 cc. of an aqueous solutioncontaining 00077-2026 mol/ Third Added Y. 1d f liter of chloroplatinicacid, followed by vaporizing to iltriionent (irgi amatigs 5 dryness andcalcining at 550 for 3 hours. Example catalyst h y Stam t 1 (molar Asshown in Table 1I, following, the resulting catalyst (e ement) weg t) gma em percent) had a composition of 0.3-1.0 Wt. percent Pt; 0.3-5.0 Wt.0.5 LiCl 69.1 percent Pb and A1203, while Pb/Pt ratio was within the 0.5NMCOi 68.0 f 5 5 O 1.3 (1350150055100 55.1 fange 0 3(1) gaggai-mm ggg 10After 10 cc. of the resulting catalyst were heated at 012 Zmoigo 5510530 C. under a hydrogen stream for 2 hours, a mixed g@ ggg): ggg gasconsisting of hydrogen and naphtha having a com- OI 52,012.23@ 751position shown below in a molar ratio of 7:1 was passed 5-3 CTO: 6&1through the catalyst layer maintained at 500 C. under 1.5 HQMOAAHQO 67.52 1 5 WC13 6,5 9 15 a total reaction pressure of 5 lig/cm. at a liquidhourly 0.3 Rech 6v- 2 space velocity of 1.5 hrrl. Reaction results after20 hours 0.05 Buon 53.9

0 1 RhC134H20 55 7 0f Operation are tabulated 111 Table II. 0.3Paoli-21320 08.0 U H014 54-0 Composition of naphtha (vol. percent):

;1}Rbiso1+ZnCh 09.2 Param 655 Sn g2g Geol., suoli-2R10 75.4 20 Oln 02 26Rigi-211+ o.i+o.(i)4 nusoiznoiioscii 70.0 Naphthen 237 S 27 None 63*Aromatics 10.6

*Dissolved in HC1. BP (o C), 88189 TABLE II Concentration of- Weightpercent Lead nitrate Chloro- Weight percent Pb/Pt Overall Solution (mollplatinic acid (wt Liquid aromatic Run number liter) (mol/liter) Pt Pbratio) yield yield 1 0.0072 0.0077 0.3 0.3 1.0 86.2 77.4 2. 0. 01450.0077 0. 3 0. e 2. o 87. 9 71. 7 3- 0. 0217 0. 0077 o. 3 0. 9 3. 0 s?.0 52. 2 4. 0.0072 0. 015 o. e 0. a 0. 5 85. 0 75. 3 5- 0. 0145 o. 015 0.e 0. 5 i. 0 85. 1 77. o e. 0. 029 0. 015 o. o i. 2 2. 0 S7. 5 72. 0 70.043 0.015 0.5 1.8 3.0 57.1 63.5 s (eomparanve).- 0. 05s 0.015 o. e 2.4 4.0 87. 0 47. 2 9 0. 024 0. 020 i. o 1.0 1. 0 83. 0 76. 0 1o..-. 0.049 0. 025 1. 0 2. 0 2. 0 85. 3 75. 5 11 0. 073 0. 02s 1.0 3. 0 e. o se.7 se. 1 i2 (comparativ 0.122 0.020 1.o 5 0 5 0 87.4 41.5 13(comparative). 0. 0077 0. 3 84. 1 47. 3 14 (comparative). 0.015 0.5 70.051. 2 15 (comparative) 0.026 1.0 77.9 62. 6

Example 28 .In 200 cc. of an aqueous solution containing 0.0128mol/liter of chloroplatinic acid and 00036-00605 mol/ liter of leadnitrate were immersed 140 cc. of ry-alumina having a particle size of2-3 mm. diameter as a carrier. The resulting product was evaporated todryness, and then calcined at 550 C. for 3 hours. As shown in Table I,following, compositions of the resulting catalysts are 0.5 wt. percentPt; 0.l5-2.50 wt. percent Pb and A1203, while Pb/Pt ratio is from 0.3 to5.0. After cc. of the resulting catalyst were heated at 500 C. in thepresence of hydrogen for 2 hours, a mixed gas consisting of hydrogen andn-heptane in a molar ratio of 3:1 was passed through the catalyst layermaintained at 490 C. under atmospheric pressure at liquid hourly spacevelocity of 0.5 hr.1. As a result, molar yields of various reactionproducts were as shown below.

Example 30 In 200 cc. of an aqueous solution containing 0.0121 mol/literof lead chloride were immersed cc. of 'yalumina as a carrier. Theyresulting product was vaporized to dryness, calcined at 550 C. for 3hours, and, subsequently, immersed in 200 cc. of an aqueous solutioncontaining 0.0128 mol/liter of chloroplatinic acid, followed byvaporizing to dryness and calcining at 550 C. for 3 hours.

The resulting catalyst had a composition of 0.5 wt. percent Pt; 0.5 wt.percent Pb and A1203, while Pb/Pt ratio is 1.0.

After 20 cc. of the resulting catalyst were heated at 500 C. in thepresence of hydrogen for an hour, a mixed gas consisting of hydrogen andn-heptane in a molar ratio of 5:1 was passed through the catalyst layermaintained TABLE I Concentrations in aqueous i solution Amount Overallyield of Pb Pb/Pt of benzene,

Chloro- Lead added ratio toluene xyleno platinc acid nitrate wt. (byproduced (mol Run number (mol/liter) (mol/liter) percent) wt.) percent)6 (comparative) 0. 0128 0. 0505 2. 50 5. 0 23. 1

7 (comparative) 0. 0128 0 0 25. 3

Example 29 at 500 C. under atmospheric pressure at a liquid hourly In200 cc. of an aqueous solution containing 0.0072- 0.122 mol/liter oflead nitrate were immersed 140 cc. of

space Velocity of 0.5 hr.1.

As a result, the molar yield of total aromatic hydrofy-alumina having aparticle size of 2-3 mm. diameter as 75 carbons produced based oriheptane was 78.3%.

Data shown in Tables I and II are also shown graphically in theaccompanying figure.

COMPARATIVE EXAMPLE 1 20 cc. of a known catalyst comprising 0.5% Pt and99.5 'y-alumina were heated at 500 C. under a hydrogen stream for anhour. Then, there was passed a mixed gas consisting of hydrogen andn-heptane in a molar ratio of 3:1 through the catalyst layer maintainedat 500 C. under atmospheric pressure at a liquid hourly space velocityof 0.5 hr.-1. As a result, molar yields of the resulting products wereas follows:

Reaction products (percent):

Aromatics:

Benzene 4.5

Toluene 17.6 Xylene 3.1 C9+ aromatics Trace Total aromatics 25.3 C-C7parafns 40.8

Gaseous component:

Methane 8.5 Ethane 6.7

Propane 6.6 Propylene 0.8 Butane 10.0

Total C1-C4 32.6

Due to a drastic decrease in catalyst activity experienced in theinstant reaction, the results shown above were values obtained afteroperation of an hour.

COMPARATIVE EXAMPLE 2 Twenty milliliters of a known catalyst consistingof 0.5% platinum and 99.5% y-alumina were heated under hydrogen at 500C. for 1 hour. Through the catalyst layer was passed a gaseous mixtureof hydrogen and n-heptane at an LHSV of 0.5 hr.-1 under atmosphericpressure, while maintaining the layer at 510 C. Molar yields of theproducts were: Benzene 8.7%, toluene 36.7%, xylenes 3.8% and the totalaromatics 49.2% after a reaction time of 1 hour.

COMPARATIVE EXAMPLE 3 Composition of the naphtha source (percent byvolume):

Paraiiins 48.3 Olens 0.4 Naphthenes 38.6 Aromatics 12.7

What is claimed is:

1. Method of producing aromatic hydrocarbons which compriseshydroforming a mixture of hydrogen and a hydrocarbon over a catalyst ata temperature of from 300 C. to 650 C. under a pressure of from 5 to 20kg./cm.2, said catalyst consisting essentially of from about 0.01 toabout 5 wt. percent platinum and from about 0.01 to about 5 wt. percentlead, up to about 1% by weight of a component selected from the groupconsisting of lithium, sodium, potassium, rubidium, cesium, beryllium,magnesium, calcium, strontium, barium, zinc, cadmium, mercury,germanium, bismuth, chromium, molybdenum, tungsten, uranium, rhenium,ruthenium, rhodium, palladium, osmium and iridium, up to 2.0% by weightof a halogen and a carrier, wherein the ratio of lead to platinum iswithin the range of from 0.1 to 3.0, and being prepared bysimultaneously supporting said platinum and lead components on a carrierby impregnation, or first supporting said lead component on a carrier byimpregnation and thereafter supporting said platinum component on saidcarrier by impregnation.

2. Method according to Claim 1 wherein said hydrocarbon is a memberselected from the group consisting of naphtha, kerosene and light oil.

3. Method according to Claim 1 wherein said hydroforming is carried outunder reaction conditions including a temperature ranging from 430 C. to550 C., and an LHSV ranging from 0.2 to l0 hrl.

4. Method according to Claim 1 wherein said platinum component is acompound of platinum and halogen.

5. Method according to Claim 1, wherein the halogen is chlorine and theamount of chlorine contained in the catalyst is in the range of 0.1-2.0%by weight based on the total Weight of catalyst components.

6. Method according to Claim 1 wherein said carrier is a member selectedfrom the group consisting of alumina, alumina hydrate, alumina gel,silica-alumina and a zeolite.

7. Method according to Claim l4 wherein said catalyst is treated withhydrogen-containing gas in the Vicinity of the reaction temperatureprior to hydroforming.

8. Method of producing aromatic hydrocarbons which compriseshydroforming a mixture of hydrogen and a hydrocarbon ofver a catalyst ata temperature of from 300 C. to 650 C. under a pressure of from 5 to 20kg./cm.2, said catalyst consisting essentially of from about 0.01 toabout 5 wt. percent platinum and from about 0.01 to about 5 wt. percentlead and a carrier, wherein the ratio of lead to platinum is within therange of from 0.1 to 3.0, and being prepared by simultaneouslysupporting said platinum and lead components on a carrier byimpregnation, or rst supporting said lead component on a carrier byimpregnation and thereafter supporting said platinum component on saidcarrier by impregnation.

References Cited UNITED STATES PATENTS 2,378,209 6/ 1945 Fuller et al260-6735 2,441,297 5/ 1948 Stirton 260-668 2,500,146 5/1950 Fleck et al260-668 3,000,811 9/ 1961 Murray et al 208-90 3,607,728 9/ 1971 Wilhelm208-111 3,425,792 2/ 1969 Stephens 23-2 3,649,565 3/ 1972 Wilhelm252-466 PT 3,686,340 8/1972 Patrick et al 260-672 R 3,670,044 6/1972Drehman et al 260-683.3

DELBERT E. GANT Z, Primary Examiner S. L. BERGER, Assistant ExaminerU.S. Cl. X.R.

208-138; 252-441, 455 R, 455 Z, 466 PT

